1. Field of the Invention
This invention relates to systems for determining cardiac functionality within a living subject, and, more particularly, to systems for calculating cardiac functionality from four dimensional data employing tissue segmentation.
2. Description of Related Art
Typically blood flow and cardiac function in living subjects has been analyzed with ultrasound, X-ray and computed axial tomography (CAT) with contrast agents, magnetic resonance (MR) imaging and other various modalities. Blood velocity, a quantitative measure of blood flow through vessels, cardiac ejection fraction (the ratio of ventricle chamber volume of relaxation vs. contraction), total cardiac output, and cardiac enlargement are parameters of interest which are significant in determining cardiac disease and failure.
Past techniques measure flow by determining blood velocity, by ultrasound doppler methods, for example, and then, vessel cross sectional area and calculate blood flow rates.
Methods for determining volumes of cardiac chambers, for instance, involve cardiac gating and two or three dimensional imaging. These may be MR, CAT scans, even positron emission tomography (PET). The areas of interest of a slice of data obtained at a specific time during the cardiac cycle are traced by hand by an operator on a computer screen for each image slice, and for all cardiac time instants of interest. This is inaccurate since the boundary between the inside of the chamber and the chamber wall may be obscured since the contrast may not be so great.
Presently there is a need for a non-invasive method of accurately determining cardiac functionality.